Design Synthesis And Self Assembly Of Dendritic Rod Like Molecules With Precisely Controlled Compositions Interactions And Topologies
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Design Synthesis And Self Assembly Of Dendritic Rod Like Molecules With Precisely Controlled Compositions Interactions And Topologies
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Author : Ruimeng Zhang
language : en
Publisher:
Release Date : 2019
Design Synthesis And Self Assembly Of Dendritic Rod Like Molecules With Precisely Controlled Compositions Interactions And Topologies written by Ruimeng Zhang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Composite materials categories.
Design Synthesis And Geometry Directed Self Assembly Of Oligo Fluorene Based Giant Molecules
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Author : Xiaoyun Yan (Chemist)
language : en
Publisher:
Release Date : 2020
Design Synthesis And Geometry Directed Self Assembly Of Oligo Fluorene Based Giant Molecules written by Xiaoyun Yan (Chemist) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Oligomers categories.
Shapes of nano-objects matter significantly during their self-aggregation process. Other than the chemical compositions, people start to recognize such geometric effects of the basic building in all aspect blocks fundamentally drive the system into diverse mesostructures. Huge amount of research effects have been paid in the investigation of geometric effects in physiochemical systems. Depending on their length-scales, the effects lying under the geometry of nano-building blocks are demonstrated in directional interactions, shape-persistent molecules/molecular fragments, and larger nanoparticles/colloids. They are in all dimensions and at all scales, which largely ravel the problem and necessitate a prototype system to be scientifically designed and systematically studied. The molecular LEGO approach, therefore, becomes crucial. This approach was conceptualized by the modular synthesis and precise architecture while constructing the shape determined nano building blocks. By finely altering the functional groups at the atomic level, the yielded molecules would form a systematic library and therefore greatly facilitate the following study towards their self-assembly behaviors. In this dissertation, we would follow this approach to demonstrate the essential features of geometric effects in self-assembly. To grab the pivotal principle of them, we choose a simple shape-persistent fragment-"rod-like" motif and studied its interplay with other geometric units. In the following sections, the detailed experimental methods, conditions, and characterization data are presented. Three general molecular arrangements are adopted: rod-coil, rod-sphere-coil and rod-sphere. Within them, some subtypes of molecular geometries (e.g. I-shaped, T-shaped geometries based on the attachment modes) are also investigated. Based on the morphologies obtained, a strong correlation between the self-assembly behavior and molecular architectures are constructed. For the rod-coil molecules, a propensity to form a layered structure was observed. The introduced rod-like unit largely expend the region of the lamellar phase. For rod-sphere-coil arrangement, since the introduced hydrophilic spherical motifs are bulky, a framework like structure was observed. In this structure, multiple molecules come together to form the molecular bundles which then ligate with each other forming the hexagonally arranged cell. A similar phenomenon was observed in the formation of the novel bicontinuous phase. Based on the highly complex texture captured under TEM, we speculate a novel network like structure was involved. Similarly, when a longer coil part was introduced, a highly asymmetric lamellar structure was formed. To our knowledge, this is the system that achieves the largest asymmetric ratios among all systems. This interesting phase behavior was rationalized by the transition from a double-layered hydrophilic domain to a single-layered hydrophilic domain which entropically stabilizes the structure. In the last, we investigate the self-assembly of rod-sphere conjugates in solution. Novel morphologies, including bilayer vesicles, interdigitated nanosheets, and hexagonally structured colloids were obtained. We attribute the abundant yielded phases by modulating geometric parameters to variant mismatching interfacial areas. From a thermodynamic perspective, the delicate balance between bending energy and interfacial energy determines the final structure. The experimental studies were carried out in either bulk or solution suggesting the principles would be widely applied. Also, these studies indicate that "bottom-up" self-assemble based on well-defined giant molecules approach can be rather powerful to fabricate usually complicated hierarchical structures and open up a wide field of supramolecular self-assembly with unexpected structure and properties.
Design Synthesis And Self Assembly Of Giant Molecules Including Giant Surfactants And Giant Tetrahedrons Based On Poss Nanoparticles
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Author : Wenpeng Shan
language : en
Publisher:
Release Date : 2018
Design Synthesis And Self Assembly Of Giant Molecules Including Giant Surfactants And Giant Tetrahedrons Based On Poss Nanoparticles written by Wenpeng Shan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Macromolecules categories.
The self-assemble behavior of various giant surfactants with different functionalities and molecular architectures, which consist of compact and rigid molecular nanoparticles (MNPs) as head and flexible polymer chains as tail, is systematically studied. The benefit of utilizing MNPs comparing with AB type di-block copolymer which has become the model for probing microphase separation in bulk state is that the MNPs could be versatile functionalized at will to fabricate functional materials via collective secondary interactions. Herein, we investigated the effect of rigid-rod junction between two blocks of giant surfactants in bulk state using small angle X-ray scattering and transmission electron microscopy. Besides the segmental interaction (x, Flory-Huggins parameter) and volume fraction of one component (f), the interfacial energy takes a vital role in the process of self-assembly. By way of about 1 nm rigid-rod junction inserted into the giant surfactant system, the pathways of order-order phase transition (OOT) could be varied due to different molecular weight of polystyrene attached inducing diverse levels of gibbs free energy with temperature increasing, one proceeds from lamellar structure (LAM) directly to the hexagonally packed cylinder structure (CYL), one passes by the double gyroid structure (DG), another one travels from LAM to hexagonally perforated layer structure (HPL), then DG, finally reaches to the stable state, CYL that possesses the most curved interfacial area in these previous mentioned structures. And the model which describes these sorts of phase behaviors with interfacial tension and packing frustration competing each other could be verified via the phenomena that curved lamellar defects observed both in bright field TEM image and small angle x-ray scattering data, which could be occurred due to the relaxation of polymer chains promoting the increase of interfacial area without loosening the imbalance of chain crowding because of tightly packed MNPs to stimulate the OOT. This prototype of phase transition supporting a fully described phase diagram provides clues to control polymer self-assembly and fine-tune the morphology and phase behaviors at the nanometer scales. In the second topic, the giant tetrahedron was fabricated on the adamantane core, same as the mechanisms of disk shape molecules forming spherical phase structures, the steric hindrance from POSS cages impeded the growth of cylindrical columns, and spherical phase structures could be achieved based on the experimental data of BCC structure appearing. And this type of fabricating spherical phase structures could pave another road to get Frank-Kasper phases with different sizes of spheres.
Manipulation Of Self Assembled Nanostructures From Molecular Janus Particles Based On Polyoxometalates Polyhedral Oligomeric Silsesquioxanes And 60 Fullerene
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Author : Hao Liu
language : en
Publisher:
Release Date : 2015
Manipulation Of Self Assembled Nanostructures From Molecular Janus Particles Based On Polyoxometalates Polyhedral Oligomeric Silsesquioxanes And 60 Fullerene written by Hao Liu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Fullerene polymers categories.
The ability to manipulate self-assembly behaviors of molecular building blocks is the key to precise "bottom-up" fabrication of desired nanostructures. In this dissertation, we focus on the rational design, facile synthesis, and self-assembly of a series of molecular Janus particles (MJPs) constructed by chemically linking a-Keggin-type polyoxometalate (POM), Lindqvist-type POM, polyhedral oligomeric silsesquioxane (POSS) derivatives and [60]fullerene (C60) derivatives. This dissertation contains two sub topics. The first one describes a rational strategy to obtain self-assembled two-dimensional (2D) nanocrystals of MJPs with definite and uniform thickness. Three different types of MNPs, namely POSS derivative, C60 derivative, and Lindqvist-type POM, are used as building blocks to construct several amphiphilic molecular Janus particles by covalently connecting hydrophobic crystalline BPOSS with a charged hydrophilic MNP. The formation of 2D nanocrystals with an exact thickness of double layers of molecules is driven by directional crystallization of the BPOSS MNP and controlled by various factors such as solvent polarity, number of counter ions, and sizes of the MNPs. Strong solvating interactions of the ionic MNPs in polar solvents (e.g., acetonitrile and dimethylformamide) are crucial to provide repulsive interactions between the charged outlying ionic MNPs and suppress further aggregation along the layer normal direction. The number of counter ions per molecule plays a major role in determining the self-assembled morphologies. Size matching of the hydrophobic and ionic MNPs is another critical factor in the formation of 2D nanocrystals. Self-assembly of rationally designed molecular Janus particles provides a unique "bottom-up" strategy to engineer 2D nanostructures.In the second sub topic, the facile synthesis and solution self-assembly behaviors of another series of MJPs are discussed. a-Keggin type POM nanoclusters and isobutyl-substituted BPOSS cages are covalently connected at 1:1, 1:2 and 1:4 ratios to construct Keggin-BPOSS, Keggin-2BPOSS, and Keggin-4BPOSS in high yields. Self-assembled nanostructures of these precisely-defined MJPs are resulted from the competing crystallization processes of the POM and the BPOSS building blocks. Since the Keggin-type POM nanocluster is slightly larger than BPOSS in the cross-section areas perpendicular to the long axis of the MJPs, crystallization of Keggin-BPOSS in the acetonitrile/water mixture was mainly directed by the POM building block, leading to an interesting "micellar-crystal" transition towards one-dimensional (1D) nanobelts. Directional crystallization of the BPOSS cages, however, dominated the self-assembly of Keggin-2BPOSS and Keggin-4BPOSS in their methanol/chloroform mixtures where the cross-section area of the Keggin POM nanocluster is smaller than those of 2BPOSS and 4BPOSS perpendicular to the long axis of the MJPs, and resulted in the formation of 2D nanosheets with exactly two layers of MJPs constructed in a head-to-head structure along the thickness normal. The distinct results manifest that the self-assembly of these MJPs could be controlled by the directional crystallization of the dominating building blocks. A rational strategy may thus be possible: we can purposely control and tune diverse unconventional nanostructures via design and synthesis of those giant molecules which follow defined chemical and physical principles of self-assemblies.
Design Synthesis And Bio Relevant Applications Of Zwitterionic Amphiphilic Macromolecular Assemblies
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Author : Rajasekhar Reddy Rami Reddy
language : en
Publisher:
Release Date : 2015
Design Synthesis And Bio Relevant Applications Of Zwitterionic Amphiphilic Macromolecular Assemblies written by Rajasekhar Reddy Rami Reddy and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Supramolecular nanoassemblies capable of reducing non-specific interactions with biological macromolecules, such as proteins, are of great importance for various biological applications especially for targeted drug delivery therapeutics. Recently, zwitterionic materials have been shown to reduce non-specific interactions with biomolecules, owing both to their charge neutrality and their ability to form strong hydration layer around zwitterions via electrostatic interactions. This dissertation focuses on design, synthesis, thorough characterization, and applications of zwitterionic amphiphilic dendrimers and polymeric materials. Firstly, A new triazole-based zwitterionic moiety was conceived and incorporated as the hydrophilic functionality in facially amphiphilic dendrons. Self-assembly characteristics and the structural and functional characteristics of the zwitterionic dendrons were then evaluated by spectroscopic techniques and by comparison with the corresponding charge-neutral PEG and anionic carboxylate-based dendrons respectively. Surface charge measurements, temperature sensitivity and evaluation of interactions of these assemblies with proteins form the bases for these comparisons. Because of the charge neutral characteristics of zwitterionic moieties exposed to outer aqueous phase, these dendritic assemblies evade non-specific interactions with biological milieu while enhancing the responsiveness towards specific biological triggers, such as proteins. We further simplified this molecular design by developing synthetically accessible zwitterionic carboxybetaine based amphiphilic polymers. Zwitterionic amphiphilic polymers are synthesized in a simple one-pot reaction by treating reactive acrylate polymer with secondary amine and 2-bromoaceticacid. This zwitterionic polymer possesses hydrophilic glycinebetaine and hydrophobic decyl chains placed orthogonally and forms environment dependent self-assembled aggregates owing to its amphiphilicity. The zwitterionic assemblies stably encapsulate guest molecules and undergo pH-dependent zeta potential and size variations owing to the pH sensitivity of zwitterionic component. In a related project, we've developed degradable polycarbonate based amphiphilic polymers possessing hydrophilic peg and hydrophobic decyl components. This degradable polymers form self-assembled aggregates encapsulate hydrophobic guest molecules, undergo degradation upon changes in pH or in presence of enzymes (PLE, an esterase). Work is underway towards the design and synthesis of zwitterionic amphiphilic degradable polymers and their characterization. Over all the work presented in this thesis have implications in design and development of polymeric excipients for targeted drug delivery, controlled release of drugs, and stimuli-sensitive therapeutics.
Study Of Self Assembly And Stimuli Responsive Behavior In Polymeric And Dendritic Amphiphiles
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Author : Poornima Rangadurai
language : en
Publisher:
Release Date : 2018
Study Of Self Assembly And Stimuli Responsive Behavior In Polymeric And Dendritic Amphiphiles written by Poornima Rangadurai and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
Natural processes are intricately detailed and able to convert molecular-level events into macroscopic or visually observable properties. This is made possible through multiple interactions at the molecular level, signaling due to covalent and non-covalent interactions, and supramolecular networks that rely on dynamic, non-equilibrium structures. Detailing processes in this manner is the current quest for material science research and designing materials for this purpose is usually via a key process known as self-assembly. Self-assembly is a process in which a material with varied components organizes itself into a particular pattern due to various specific inter and intra molecular interactions. By understanding this process, scientists have developed methods to predict the patterns formed (morphologies) depending on the molecular construct of the material, and impart a broad range of responsive behavior to these self-assemblies, for several different applications. The goal of this thesis was to investigate the different parameters and stimuli that affect the morphology of these assemblies, either transforming them, perturbing them or, destroying them completely, and the outcome of this event. Polymeric and dendritic amphiphiles were chosen as scaffolds for this purpose of building stimuli responsive assemblies, as they provide handles for innovative modifications and engineering of various stimuli-sensitive groups. Both offer unique advantages, polymers offering low critical aggregation concentrations and ease of synthesis, and dendrimers having uniform dispersity and exact synthetic reproducibility. Amphiphilic homo-polymers were designed to respond to an environmental pH change, and degrade, expelling the non-covalently held contents. However, a temporal degradation of its backbone, resulted in a change of its hydrophilic-lipophilic balance (HLB) and hence, its self-assembled morphology. Light-sensitive amphiphilic block co-polymers, with an ability to form equilibrium assemblies when dispersed in aqueous media were also explored. The reversible conformational change brought about by the light-actuation, in one azobenzene molecule placed at the interface of the hydrophilic and hydrophobic blocks, was able to transduce motions throughout the polymer chains, resulting in a change in the material's permeability. This system's ability to function far-from-equilibrium, i.e. work only in the presence of an energy input and rest in a dormant state in its absence, was also explored. This thesis also investigated the response of this polymer to stimuli such as pH and proteins that brought about an irreversible covalent modification to the system, as opposed to the light stimulus. Signaling through non-covalent based interactions, akin to nature, causing release of non-covalent guest contents was also explored using dendritic and block co-polymer amphiphiles. In the case of the dendrimer, the looming challenge of bacterial targeting was addressed by harnessing a membrane protein-ligand interaction. Block co-polymers were used to understand the effect of non-covalent binding on the fidelity of an assembly with a high degree of chain-entanglements and a densely hydrophobic core.
Dendrimers And Other Dendritic Polymers
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Author : Jean M. J. Fréchet
language : en
Publisher: John Wiley & Sons
Release Date : 2001
Dendrimers And Other Dendritic Polymers written by Jean M. J. Fréchet and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with Science categories.
With contributions from many of the world's leading scientists in the field of dendritic research and development, Dendrimers and Other Dendritic Polymers provides a comprehensive review of this rapidly expanding and exciting new field of polymer science. Of interest to academia and industry alike, this book covers the synthesis, characterization, unique properties, potential for novel applications and technical challenges associated with these polymers. * Detailed coverage of all known subclasses of dendritic polymers, including their properties and synthesis * Insight into the potential commercial applications of dendritic polymers, including drug delivery, cancer therapy, coatings and adhesives * Identification of the key trends and perspectives in dendrimer research * Essential reference for polymer chemists, materials scientists and plastics engineers working in academia and industry alike
Transport In Biological Media
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Author : Sid M. Becker
language : en
Publisher: Newnes
Release Date : 2013-05-21
Transport In Biological Media written by Sid M. Becker and has been published by Newnes this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-05-21 with Technology & Engineering categories.
Transport in Biological Media is a solid resource of mathematical models for researchers across a broad range of scientific and engineering problems such as the effects of drug delivery, chemotherapy, or insulin intake to interpret transport experiments in areas of cutting edge biological research. A wide range of emerging theoretical and experimental mathematical methodologies are offered by biological topic to appeal to individual researchers to assist them in solving problems in their specific area of research. Researchers in biology, biophysics, biomathematics, chemistry, engineers and clinical fields specific to transport modeling will find this resource indispensible. Provides detailed mathematical model development to interpret experiments and provides current modeling practices Provides a wide range of biological and clinical applications Includes physiological descriptions of models
Polymer Science And Engineering
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Author : National Research Council
language : en
Publisher: National Academies Press
Release Date : 1994-01-01
Polymer Science And Engineering written by National Research Council and has been published by National Academies Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994-01-01 with Technology & Engineering categories.
Polymers are used in everything from nylon stockings to commercial aircraft to artificial heart valves, and they have a key role in addressing international competitiveness and other national issues. Polymer Science and Engineering explores the universe of polymers, describing their properties and wide-ranging potential, and presents the state of the science, with a hard look at downward trends in research support. Leading experts offer findings, recommendations, and research directions. Lively vignettes provide snapshots of polymers in everyday applications. The volume includes an overview of the use of polymers in such fields as medicine and biotechnology, information and communication, housing and construction, energy and transportation, national defense, and environmental protection. The committee looks at the various classes of polymersâ€"plastics, fibers, composites, and other materials, as well as polymers used as membranes and coatingsâ€"and how their composition and specific methods of processing result in unparalleled usefulness. The reader can also learn the science behind the technology, including efforts to model polymer synthesis after nature's methods, and breakthroughs in characterizing polymer properties needed for twenty-first-century applications. This informative volume will be important to chemists, engineers, materials scientists, researchers, industrialists, and policymakers interested in the role of polymers, as well as to science and engineering educators and students.
Photoreactive Organic Thin Films
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Author : Zouheir Sekkat
language : en
Publisher: Elsevier
Release Date : 2002-12-07
Photoreactive Organic Thin Films written by Zouheir Sekkat and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002-12-07 with Technology & Engineering categories.
Wolfgang Knoll is a former Directory of Polymer research at the Max Planck Institute. He is extremely well know for his research in this area. Zouheir Sekkat was a Postdoctoral researcher at Max Planck working under Professor Knoll. With Knoll's involvement, we can be confident that the best people in this field will be contributing to the reference.